The present invention relates to a fluorochemical composition to impart water and/or oil repellency to a substrate, in particular to a fibrous material such as textile or leather. In particular, the present invention relates to fluorochemical compositions that are based on fluoroaliphatic and hydrocarbon radical containing condensates of an amino resin. The present invention also relates to a method of making these condensates and to a method of treatment of a substrate therewith.
Organofluorine compounds (i.e., fluorochemicals) are substances containing portions that are fluorocarbon in nature (e.g., hydrophobic, oleophobic, and chemically inert) and portions that are organic or hydrocarbon in nature (e.g., chemically reactive in organic reactions). Some fluorochemicals are familiar to the general public, such as SCOTCHGARD(trademark) carpet protector, which imparts oil and water repellency and stain and soil resistance to carpet. Other such substances have various industrial uses, such as reducing the surface tension of liquids, reducing evaporation and inflammability of volatile organic liquids, and improving the leveling of organic polymer coatings.
The utility of organofluorine compounds as surface-active agents (i.e., surfactants) and surface-treating agents is due in large part to the extremely low free-surface energy of a C6-C12 fluorocarbon group, according to H. C. Fielding, xe2x80x9cOrganofluorine Compounds and Their Applications,xe2x80x9d R. E. Banks, Ed., Society of Chemical industry at p. 214 (1979). Generally, the organofluorine substances described above are those which have carbon-bonded fluorine in the form of a monovalent fluoroaliphatic radical such as a perfluoroalkyl group, typically CnF2n+1, where n is at least 3, the terminal part of which group is trifluoromethyl, xe2x80x94CF3.
Fluorochemical based water and/or oil repellent compositions for treating substrates, in particular textiles and leather are of substantial commercial importance. Amongst water and/or oil repellent compositions known in the art to treat substrates are those based on amino resins and in particular condensates of formaldehyde and melamine. For example, an aqueous emulsion of fluorochemical containing melamines (FC-melamine) is commercially used as an oil and water repellent. However, due to the poor solubility of the FC-melamines in common organic solvents, it is generally required to first dissolve the FC-melamine in a fluorinated solvent or a chlorofluorinated solvent and then disperse that solution in water in the presence of an emulsifier using high energy emulsifying equipment. The solvent can subsequently be recovered via distillation. Such procedure is cumbersome, expensive and moreover requires the use of environmentally unacceptable solvents.
DE 3133303 describes FC-melamines that are obtained by condensation of highly etherified hexamethylolmelamine and a perfluorinated thiol. These compounds can be used in the form of an aqueous emulsion to treat textiles and leather in order to provide water and oil repellency thereto. While good results can be obtained on textiles, the results of such FC-melamines on leather leaves a desire for further improvement. Moreover, as set out above, these compounds are generally only soluble in fluorinated solvents.
U.S. Pat. No. 3,510,455 teaches the production of thermosettable fluorinated prepolymers by reacting an aldehyde, a nitrogen compound, e.g. urea or melamine, and a fluorinated aliphatic compound which contains a perfluorinated alkyl chain as well as at least one functional group with an active hydrogen atom. These prepolymers are soluble in usual solvents and cure on polar surfaces to continuous, adherent films. The prepolymers prepared according to this patent are not believed to be suitable for the treatment of textile materials.
U.S. Pat. No. 3,362,782 teaches the application of condensation products of optionally etherified methylolated compounds of heterocyclic nitrogen compounds with 1,1-dihydroperfluoroalkyl alcohols or perfluorocarboxylic acid amides, e.g. with perfluoroheptyloxymethylpenta-(methoxymethyl)-melamine for the anti-soiling finishing of cellulose textile material. For the application an organic solvent is used. However, the oil-and water-repellent effects achieved with these condensation products do not meet the present requirements. Moreover, unproportionally large quantities of these condensation products have to be used.
Fatty acid derivatives of melamine are disclosed in U.S. Pat. No. 3,506,661 to treat textiles and in particular for water repellent impregnation. These melamine derivatives are said to be soluble in chlorated hydrocarbons, in aromatic hydrocarbons such as benzene, benzol and toluol. However, these compounds are unsuitable as oil repellents and also do not provide the presently desired water repellency on textiles.
U.S. Pat. No. 3,480,579 discloses the use of condensates of hexaalkyloxymethyl melamines and long chain aliphatic acids in a composition to impart water repellency to a textile. According to this disclosure, the composition preferably also contains a fluorinated oil and water repellent compound in particular a polymeric, fluorine containing aliphatic compound.
U.S. Pat. No. 5,292,796 discloses fluorochemical compositions comprising fluorinated compounds, wherein the fluorinated compound comprises a fluorochemical oligomeric portion bonded through xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x80x94NHxe2x80x94 or CO2xe2x80x94 to a moiety comprising a group derived from an amino resin. Particularly disclosed amino resins include methylolated melamines, benzoguanamines and acetylguanamines and methylated derivatives thereof The compositions can be used to impart durable abrasion-resistant oil and water repellent properties. Further, according to the teaching of this patent, the amino resin may contain a long chain aliphatic group, and, if desired to increase the hydrophobic character of a substrate to be treated, it is possible to include compounds such as fatty acid condensates with melamine or urea derivatives. According to the examples in this patent, the fluorochemical is dissolved in hexafluoroxylene and the resultant solution is emulsified in water with the aid of a surfactant.
The present invention provides a fluorochemical composition that is readily soluble in non-fluorinated organic solvents and that can provide good and/or improved water and/or oil repellency on substrates, particularly textile or leather substrates.
The fluorochemical composition comprises one or more condensates of (i) a methylolated amide or an alkoxylated derivative thereof, (ii) a hydrocarbon compound selected from an alcohol, a thiol, an amide or an acid having a hydrocarbon group of at least 6 carbon atoms and which hydrocarbon group is optionally substituted with up to 3 substituents and (iii) a fluorinated compound corresponding to formula (I):
Rfxe2x80x94(Xl)nxe2x80x94Zlxe2x80x83xe2x80x83(I)
wherein:
Rf represents a fluorinated aliphatic group;
Xl represents an organic divalent linking group;
Zl represents hydroxy, thiol, an amide group or an acid group and n is 0 or 1.
The present invention also provides the use of the fluorochemical composition to impart water repellency and/or oil repellency to a substrate.
The present invention further provides a method of treatment of a substrate with the fluorochemical composition and substrates comprising the fluorochemical composition on their surface.
Also provided is a method of making the fluorochemical composition.
The fluorochemical composition can be prepared by reacting, in the presence of an acid catalyst, (i) a methylolated amine or an alkoxylated derivative thereof, (ii) a hydrocarbon compound selected from an alcohol, a thiol, an amide or an acid having a hydrocarbon group with at least 6 carbon atoms and which hydrocarbon group is optionally substituted with up to 3 substituents and (iii) a fluorinated compound corresponding to formula (I):
Rfxe2x80x94(X1)nxe2x80x94Z1xe2x80x83xe2x80x83(I)
wherein:
Rf represents a fluorinated aliphatic group;
X1 represents an organic divalent linking group;
Z1 represents hydroxy, thiol, an amide or an acid group, such as e.g. a carboxylic acid, and n is 0 or 1.
The methylolated amines or alkoxylated derivatives thereof can be selected from the group consisting of methylolated melamines, methylolated urea, methylolated benzoguanamine, methylolated acetoguanamine or an alkoxylated derivative thereof Examples include hexamethoxymethyl melamine, trimethoxymethyl melamine, dimethoxymethyl urea, dimethoxymethyl ethyleneurea, dimethoxymethyl propyleneurea.
The alkoxylated derivatives of methylolated amines are most preferred in the present invention since they have a better stability in an acidic medium and the formation of substantial amounts of cross-linked materials during the preparation of the condensates in accordance with this invention can be avoided. Particularly preferred are C1-C4 alkoxylated derivatives and more preferably C1-C2 derivatives. The alkoxylated derivatives of methylolated amines are preferably highly etherified, i.e. preferably at least 70% and more preferably at least 90% of the alcohol groups are etherified. A highly, preferred alkoxylated derivative of a methylolated amine comprises hexamethylol melamine ether, the methylol groups of which are etherified with an alcohol containing 1 to 4, especially 1 to 2 carbon atoms. Commercially available hexamethoxymethyl melamines useful in this invention include CYMEL(trademark) 300, CYMEL(trademark) 301, CYMEL(trademark) 303 and CYMEL(trademark) 350, differing from each other in the amount of free methylol groups.
Blends of methylolated amines and/or alkoxylated derivatives thereof can also be used to prepare the fluorochemical composition.
Preferred hydrocarbon compounds for use in the preparation the fluorochemical composition can be represented by formula II
Rhxe2x80x94(X2)mxe2x80x94Z2xe2x80x83xe2x80x83II
wherein:
Rh represents a hydrocarbon group
X2 represents a divalent organic linking group
Z2 represents hydroxy, thiol or an acid group, such as e.g. a carboxylic acid, and m is 0 or 1.
The term xe2x80x9chydrocarbon groupxe2x80x9d in connection with the present invention is used to indicate not only groups consisting of hydrogen and carbon but also groups that can optionally be substituted by a functional group such as e.g. halogen, hydroxy, amino etc.
Rh includes hydrocarbon groups having at least 6 carbon atoms and more preferably at least 8 carbon atoms. These hydrocarbon groups can optionally contain 1 to 3 substituents which are preferably selected from the group consisting of chlorine, bromine, fluorine, hydroxy, amino groups, alkoxycarbonyl groups, alkoxy groups etc. More preferably however, the hydrocarbon group is unsubstituted and preferably saturated. Particularly preferred Rh-groups included unsubstituted linear or branched alkyl groups. Preferably such alkyl groups have at least 8 carbon atoms. Rh-groups may also contain cycloaliphatic groups such as cyclohexyl groups or cyclohexylene groups. In accordance with the present invention it is also possible to use a mixture of hydrocarbon compounds in the condensation reaction to make the fluorochemical composition thus yielding condensates having different hydrocarbon radicals. A preferred mixture includes a hydrocarbon compound wherein Rh is a linear alkyl group, and a hydrocarbon compound wherein Rh is a branched alkyl group.
Suitable Rf-groups for the fluorinated compounds according to formula (I) are fluorinated, stable, inert, preferably saturated, non-polar, monovalent aliphatic radicals. They can be straight chain, branched chain, cyclic or combinations thereof They can contain heteroatoms, bonded only to carbon atoms, such as oxygen, divalent or hexavalent sulfur, or nitrogen. Rf is preferably a fully-fluorinated radical, but hydrogen or chlorine atoms can be present as substituents if not more than one atom of either is present for every two carbon atoms. The Rf group has at least 3 carbon atoms, preferably 3 to 14 carbon atoms, and preferably contains about 40% to about 80% fluorine by weight, more preferably about 50% to about 78% fluorine by weight. The terminal portion of the Rf group is a perfluorinated moiety, which will preferably contain at least 7 fluorine atoms, e.g., CF3CF2CF2xe2x80x94, (CF3)2CFxe2x80x94, F5SCF2xe2x80x94. The preferred Rf groups are fully or substantially fluorinated and are preferably those perfluorinated aliphatic radicals of the formula C1F2t+1xe2x80x94 where t is 3 to 14.
Linking groups X1 and X2 in the above formulas (I) and (II) preferably contain from 1 to about 20 carbon atoms. Optionally they can contain oxygen, nitrogen or sulfur-containing groups or a combination thereof Preferably the linking groups are selected from the group consisting of straight chain, branched chain or cyclic alkylene, arylene, aralkylene, sulfonyl, poly(alkyleneoxy), urethanylene, ureylene, carbonamidoalkylene or sulfonaridoalkylene groups. Representative X1 groups are described in the following list. For the purposes of this list, each k is independently an integer from 1 to about 20, g is an integer from 0 to about 10, h is an integer from 1 to about 20, Rxe2x80x2 is hydrogen, phenyl, or alkyl group of 1 to about 4 carbon atoms, and R2xe2x80x2 is an alkyl group of 1 to about 20 carbon atoms.
xe2x80x94SO2NRxe2x80x2(CH2)kxe2x80x94
xe2x80x94CONRxe2x80x2(CH2)kxe2x80x94
xe2x80x94(CH2)kxe2x80x94
xe2x80x94CH2CH(OH)CH2xe2x80x94
xe2x80x94CH2CH(ORxe2x80x22)CH2xe2x80x94
xe2x80x94CHxe2x95x90CH2(CH2)kxe2x80x94
xe2x80x94(CH2)kO(CH2)kxe2x80x94
xe2x80x94(CH2)kS(CH2)kxe2x80x94
xe2x80x94(CH2)k(OCH2CH2)kxe2x80x94
xe2x80x94(CH2)kSO2(CH2)kxe2x80x94
xe2x80x94SO2NR(CH2)kO(CH2CH2)kxe2x80x94
xe2x80x94(CH2)kSO2NRxe2x80x2(CH2)kxe2x80x94
xe2x80x94(CH2)kSO2xe2x80x94
xe2x80x94OC6H4CH2xe2x80x94
Preferred X1 groups include xe2x80x94(CH2CH2)kxe2x80x94 and xe2x80x94SO2N(R)CH2CH2xe2x80x94 wherein k is 1 or 2 and R is a C1-C4-alkyl group. If Rf is a perfluorinated radical, a linking group (X1) is generally required.
The relative mole ratio of the fluorinated compound and the hydrocarbon compound to the methylolated amine or an alkoxylated derivative thereof in the reaction mixture can vary. Any residual alkoxy groups on the condensates of the invention can be used for crosslinking with the reactive groups, such as hydroxy or amino groups on the substrates during drying and curing step of the application. It will further be appreciated by one skilled in the art that the method of preparation of the fluorochemical composition may result in a mixture of condensates containing varying amounts of fluorochemical groups and hydrocarbon groups. Such mixture can be used in accordance with this invention without separating the various condensates.
Any acid catalyst known to be useful in condensation reactions can be used in the above described method. Typically a strong acid catalyst such as p-toluene sulfonic acid, camphene sulfonic acid, amberlyst IR-120 and methane sulfonic acid are preferred.
According to a preferred mode of carrying out the condensation, the methylolated amine or alkoxylated derivative thereof, the fluorinated compound and hydrocarbon compound are mixed and heated until a homogeneous mixtures is obtained. Subsequently, the catalyst can be added. Preferably, the reaction is carried out without addition of a solvent although it may be desirable to add high boiling solvents to lower the viscosity. The term xe2x80x9chigh boilingxe2x80x9d in connection with this embodiment means a solvent that has a boiling point well above the boiling point of the alcohol (generally methanol) formed during condensation.
During the reaction, a volatile alcohol is formed that can be removed by distillation to shift the equilibrium towards the formation of the condensates. To accomplish this, it is preferred to carry out the condensation at a temperature at least 20xc2x0 C. above the boiling point of the alcohol formed during condensation. In this particular embodiment, the condensation is carried out in two steps by (1) reacting the reaction mixture of catalyst and components (i), (ii) and (iii) at a temperature that is at least 20xc2x0 C. or more above the boiling point of the volatile alcohol formed until little or no volatile alcohol distills off the reaction mixture; and then (2) increasing the temperature of the reaction mixture by about 40 to 80xc2x0 C., preferably by about 40 or 50xc2x0 C. for an additional period which is typically one or two hours.
It is also desirable to maintain a flow of an inert gas, such as nitrogen gas, above the reaction surface of the reaction mixture to avoid foaming and to speed up the reaction.
The fluorochemical composition is soluble in various non-fluorinated organic solvents such as acetates (ethyl acetate), ethers (di-propylene glycol mono methyl ether, tetrahydrofuran, ethylene glycol ethers), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone), alcohols (methanol, ethanol, isopropylalcohol, glycols), dimethylpyrrolidone and mixtures of thereof. Accordingly, the fluorochemical composition can be used as a solution in such organic solvents or alternatively, a emulsion in water of the fluorochemical composition can be prepared according to well-known techniques. For example, a solution of the fluorochemical composition in an organic solvent, e.g. ethylacetate, gradually can be added to a solution of an emulsifier in water with vigorous stirring. The thus obtained pre-mix may then be subjected to ultrasound treatment or high shear homogenization to obtain a milky emulsion of the fluorochemical composition in water. If desired, the organic solvent can then be removed e.g. by distillation under reduced pressure.
The fluorochemical composition of this invention can be applied using conventional application methods and can be used as an aqueous emulsion. Alternatively it can be used as a treatment composition in solvent. An aqueous emulsion will generally contain water, an amount of fluorochemical composition effective to provide repellent properties to a substrate treated therewith, and a surfactant in an amount effective to stabilize the emulsion. Water is preferably present in an amount of about 70 to about 20000 parts by weight based on 100 parts by weight of the fluorochemical composition of the invention.
The surfactant is preferably present in an amount of about 1 to about 25 parts by weight, preferably about 5 to about 10 parts by weight, based on 100 parts by weight of the fluorochemical composition. Conventional cationic, nonionic, anionic, and zwitterionic surfactants are suitable.
The amount of the treating composition applied to a substrate in accordance with this invention is chosen so that sufficiently high or desirable water and oil repellencies are imparted to the substrate surface, said amount usually being such that 0.01% to 5% by weight, preferably 0.05% to 2% by weight, based on the weight of the substrate, of fluorochemical composition is present on the treated substrate. The amount which is sufficient to impart desired repellency can be determined empirically and can be increased as necessary or desired.
Various additives may be incorporated into the fluorochemical compositions of the invention to impart special properties to the treated substrate, for example, hydrocarbon extenders can be added for soil resistance; also fat liquors or synthetic tanning agents can be added.
If it is desired to improve the softness or xe2x80x9chandxe2x80x9d of a substrate treated with a composition of the invention, it is possible to use fluorine-free softeners, such as certain polyethylenes, polydimethylsiloxanes, modified hydrogenalkylpolysiloxanes, or other materials known to those skilled in the art.
It is also possible to use a composition of the invention in combination with other fluorinated products or with polymers or auxiliary products such as polyglycols, colloids such as starch, dextrin, casein, sizing agents, fixing or retaining agents, materials to improve stain resistance, cleaning ability, fire proofing or antistatic properties, buffering agents, fungicidal agents, optical bleaching agents, sequestering agents, mineral salts, surface-active agents, or swelling agents to promote penetration. Particular suitable auxiliary products and amounts thereof can be easily selected by those skilled in the art.
The substrates treated by the water and oil repellency imparting composition of this invention are not especially limited and include fibrous materials such as textile fabrics, fibers, non-wovens, leather, paper, carpet, plastic, wood, metal, glass. The fluorochemical composition is particularly useful for imparting water- and oil repellency to leather. These properties can be imparted by a drum treatment during the tanning process of the leather. The leather substrate is then typically dried for about 24 hours at room temperature and subsequently cured for about 5 to 10 minutes at 60 to 70xc2x0 C.
In order to affect treatment of a textile substrate, the substrate can be immersed in a diluted emulsion. The saturated substrate can then be run through a padder/roller to remove excess emulsion, dried and cured in an oven at a temperature and for a time sufficient to provide a cured treated substrate. This curing process is typically carried out at temperatures between about 110xc2x0 C. and about 190xc2x0 C. depending on the particular system or application method used. In general, a temperature of about 150xc2x0 C. to 170xc2x0 C. for a period of about 20 seconds to 10 minutes, preferably 3 to 5 minutes, is suitable. The cured treated substrate can be used as desired, e.g. incorporated or fashioned into a garment.